. Discuss how the combinatorial optimization methods from Chapter 3 might be used to improve tree-based methods.   . Find an example for which X = f ( τ ) + _ , where _ is a random vector with mean...

.
Discuss how the combinatorial optimization methods from Chapter 3 might be used to improve tree-based methods.

.
Find an example for which
X
=
f(τ) +

_
, where

_

is a random vector with mean zero, but
f
is not a principal curve for
X.